I am tiling the walls around the tub and shower and want to know about the use of green board vs backerboard. I have already installed backerboard from the tub lip half way up the wall right onto the studs (no extra vapor barrier). I have installed green board above that to the ceiling. I had planned to paint this section but now have decided to go all the way to the ceiling with tile. Is this installation ok, or do I need to remove the greenboard and install backerboard?
Do I need to put a vapor barrier such as roofing paper (or plastic sheeting) behind the backer board? Thank you for your help.